The present invention relates generally to a copying system, and more particularly to an apparatus and method for effecting duplex copying (including double-face and composite copying) on one copy sheet.
When a copying apparatus or any other image forming apparatus makes duplex copies on one copy sheet; for example, on both sides of one sheet, it is required to refeed the copy sheets to the image forming section after an image is formed on one side thereof. In order to refeed the copy sheets there have been many proposals; one example is disclosed in U.S. Pat. No. 4,745,439. This prior art teaches that there is provided an intermediate tray for storing the copy sheets each having an image on one side and refeeding them to the image forming section. Another example is disclosed in U.S. Pat. No. 3,862,802 which teaches that there is provided a storage means in the form of a roll-type web extended between two winders wherein the sheets are supported between adjacent layers of the web. When the web is wound around a first winder from a second winder, the sheets are delivered to an image forming section.
However, in the first-mentioned apparatus having an intermediate tray there is a need for providing a device for sorting or separating the sheets from each other, so as to feed them sheet by sheet smoothly. In the second-mentioned apparatus there is no need for providing such a sorting or separating expedient but the problem is that it is difficult to remove a jamming of the copy sheets because of the fact that the sheet refeeding apparatus is positioned at a higher place than the image forming section. Another disadvantage is that the image forming apparatus as a whole becomes large in size.